1. Technical Field
The present invention relates to a method for advanced control of batch processes.
2. Description of Related Art
Many types of products are made in batch or semi-batch processes. Often the control systems for batch processes are relatively crude compared to continuous processes. One reason for this is that it is often difficult to measure the product in a batch process. Moreover, the quality characteristics of the final product are only directly evident at batch completion. Further, as one skilled in the art would understand, often batch processes also exhibit large time constants and time varying gains and dynamics. As such, complex nonlinear dynamic models are needed for control models, which are often unavailable for industrial processes. Because it is often difficult to measure the properties of a product until the end of the batch, the basic automation system generally attempts to repeatably adhere to defined recipe conditions in the hope that these conditions will yield acceptable product. For future batches if the actual value was different than the expected value, then the recipe of the process conditions of the future batch can be adjusted. Thus, prior art batch process control systems are feedback or reactionary control systems. Such basic control systems cannot or do not proactively compensate for the incoming disturbances that are inherent in any process. As such, basic control systems in batch operations often have great variability in the final product specifications compared to continuous processes that can be continuously monitored and adjusted to meet a desired final specification. Accordingly, it is desirable to have an advanced batch control system that can offer better control over the batch system by decreasing variability. Further, it is desirable that an advanced batch control system be able to better predict and obtain desired final product properties, as well as improve process efficiency and process operability.